A large variety of products are in the form of a dispersion of an oily phase in an aqueous phase, such as in the form of an emulsion. Such is the case most particularly for cosmetic, dermatological or pharmaceutical products, these dispersions imparting good sensory properties to the skin and being easy to apply.
However, it is well known that dispersions, and in particular emulsions, lack stability over time, in particular on account of variations in temperature; these emulsions "break" giving rise to two separate phases, rendering them unusable.
The nature and the concentration of the emulsifying agent used may have a significant influence on the stability of such compositions.
However, it is well known that the choice and concentration of a suitable emulsifying agent will depend on various factors and, in particular, on the oil or oils constituting the oily phase of the dispersion or of the emulsion.
Moreover, it should be noted that certain surfactants are not free of drawbacks, in particular when they are employed at high concentration for the purpose of improving the stability.